Metadata file shows up via direct IPFS URI in browser - but not displayed as metadata of NFT item at OpenSea

Anyone have experience of this issue - I have successfully added an image and a json file to my node and pinned them. I’ve set the token URI in my smart contract for NFTs. The items are directly accessible in a browser - both the json file and the .png file. However, despite the URI being correct, the data does not display in an OpenSea listing for the item at Rinkeby testnet. I guess this is a factor of OpenSea cache or display and not something at IPFS side - esp. as I can access directly my node files - node is up and running. Any ideas appreciated.

I have the same problem on Polygon.

OpenSea support says:

Upon further checking, the image is stored on IPFS and IPFS is timing out. That being said, OpenSea is unable to read and fetch its images. This is something we can’t support as this should be fixed by IPFS.